Well folks, it’s July 1st already — the means we’re moving into “peak heat” summer conditions. It’s vitally important to keep your ammo at “normal” temps during the hot summer months. Even if you use “temp-insensitive” powders, studies suggest that pressures can still rise dramatically when the entire cartridge gets hot, possibly because of primer heating. It’s smart to keep your loaded ammo in an insulated storage unit, possibly with a Blue Ice Cool Pak if you expect it to get quite hot. Don’t leave your ammo in the car or truck — temps can exceed 140° in a vehicle parked in the sun.

To learn more about how ambient temperature (and primer choice) affect pressures (and hence velocities) you should read the article Pressure Factors: How Temperature, Powder, and Primer Affect Pressure by Denton Bramwell. In that article, the author uses a pressure trace instrument to analyze how temperature affects ammo performance. Bramwell’s tests yielded some fascinating results.

For example, barrel temperature was a key factor: “Both barrel temperature and powder temperature are important variables, and they are not the same variable. If you fail to take barrel temperature into account while doing pressure testing, your test results will be very significantly affected. The effect of barrel temperature is around 204 PSI per F° for the Varget load. If you’re not controlling barrel temperature, you about as well might not bother controlling powder temperature, either. In the cases investigated, barrel temperature is a much stronger variable than powder temperature.”

Powder Heat Sensitivity Comparison Test

Cal Zant of the Precision Rifle Blog has published a fascinating temp-stability comparison test of four powders: Hodgdon H4350, Hodgdon Varget, IMR 4451, and IMR 4166. The first two are Hodgdon Extreme powders, while the latter two are part of IMR’s new Enduron line of propellants.

Rimfire Benchrest can be fun and rewarding. It can also be frustrating because sourcing superior lots of ammo is a never-ending challenge. Still we like rimfire benchrest because you don’t need to load at the range. Plus rimfire barrels last a very long time (our friend Joe Friedrich set an ARA Benchrest record with a 100,000+ round-count barrel). Here’s a great video from the National Rimfire Benchrest Association of Ireland (NRBAI). Production quality is excellent! We highly recommend you watch this video, which does a great job illustrating both the fun and challenge of rimfire benchrest competition.

If you’ve never seen 50m Rimfire Benchrest competition, this video is well worth watching:

“If you need to get your mind away from everything… then look down a scope, concentrate, and be disciplined.”

“Comradery is one of our organization’s key traits… there are no barriers of gender, age or mobility. Just a very diverse, bunch of good people enjoying a sport together.”

“The skill, in brief, is having the ability to hit the equivalent of the top of a pinhead at 50 meters, in all conditions with a .22 round. Not easy, especially when you have to do it 50 times to get a maximum score of 500 [points], 250 per sheet.”

Credit Boyd Allen for finding this NRBAI Benchrest Video, released on 6/28/17.

Many leading shooting sports online retailers are offering money-saving promotions this holiday weekend. With appropriate discount codes you can save 10%, get free shipping, or qualify for other significant savings. Here are some of the best current promotions we’ve found. Note — these promo codes change frequently. Check www.Retailmenot.com for new codes after these expire.